Electric mat switch



March 29,1966 MK. MYILLER 3,243,540

ELECTRIC MAT SWITCH Filed Jan. 17, 1963 I n.- \N I I a i I .7'?

INVENTOR /V0/PM,4/V M/LLE/P United States Patent ELECTRIC MAT SWITCH Brothers, Upper Darby, Pa.-, a partnership Filed Jan. 17, 1963. Ser. No. 252,133

1 Claim. ((11. 206-86) The present invention relates to a treadle such as is employed for controlling an electric circuit and is concerned primarily with a treadle having structural characteristics which enable it to be designed accurately for a required sensitivity.

At the present time it is common practice to install a treadle at the entrance of a doorway or similar place for the purpose of automatically opening a door, sounding an alarm, or energizing a visual signal. The treadles now commonlyemployed require expensive and extensive installation and expense and inconvenience is experienced when it becomes necessary to make repairs. Moreover, it is difiicult to adapt the now existing treadles to a particular sensitivity depending upon the conditions of any particular installation.

With the foregoing conditions in mind, the present invention has in view as its foremost objective the provision of a treadle which takes the form of an elongated strip which while complete in itself, is susceptible of being placed under a doormat This placement and the connection of the lead wires with the circuit to be controlled is all that is required in the way of installation. Thus, when the occasion arises that repairs are to made or a change in sensitivity desired all that is necessary is to remove the strip from beneath the mat.

More in detail the invention has as an objective the provision of a treadle which includes as a characteristic element, three layers of foam rubber. The upper and lower layers are lined on their inner faces with conducting metallic foils. These foils constitute the contacts and are maintained spaced relation by the intermediate layer of foam rubber. An important feature of the invention resides in the formation of openings in this intermediate layer. It is the presence of these openings which enable the contacts to come into engagement when pressure is applied to the treadle. The size and spacings of the openings is the determining factor so far as sensitivity is concerned. Thu-s if a contact is to be achieved under light pressure, the openings are comparatively large and closely spaced. If it is desired that a contact be created only under a heavier pressure, the openings are smaller and more widely spaced.

Another objective in view is the provision of a treadle of the character indicated in which the layers of foam rubber are encased in an appropriate moisture proof casing such as vinyl. A wear-proof outer casing such as vinylcoated nylon may also be employed.

It is evident that a treadle made in accordance with the above noted objectives may be provided in strips of appropriate length and as many strips as required utilized in any particular installation. Any strip is susceptible of easy replacement for repair or a change of sensitivity as the occasion demands.

Various other more detailed objectives and advantages of the invention such as arise in connection with carrying out the above noted ideas in a practical embodiment will in part become apparent and in part be hereinafter stated as a description of the invention proceeds.

The invention therefore comprises a treadle consisting of a self contained unit in elongated strip form and including three layers of foam rubber with the inner faces of the top and bottom layers lined with metallic foil and maintained in spaced relation by the intermediate layer 3,243,540 Patented Mar. 29, 1966 which is formed with openings of required size and spacing to achieve a desired sensitivity.

For a full and more complete understanding of the invention, reference may be had to the full description and accompanying drawing, wherein:

FIGURE 1 is a diagrammatic perspective depicting one site where the treadle of this invention is installed.

FIGURE 2 is a top plan view of a portion of the treadle with various layers broken away,

FIGURE 3 is a longitudinal section illustrating the relationship of the parts when pressure is applied.

FIGURE 4 is a detailed plan view of a portion of one intermediate layer which may be applied when low sensitivity is required.

FIGURE 5 is a view similar to FIGURE 4 depicting a different arrangement of the holes when greater sensitivity is required and,

FIGURE 6 is a wiring diagram.

Referring now to the drawing and first more particularly to FIGURE 1, a wall 10 is shown as formed with the doorway 11 and a floor 12 is at the bottom of the doorway. A doormat 13 is positioned on the floor 12 in front of the doorway 11 and two strips, T and T of the treadle of this invention, are positioned between the doormat 13 and the floor 12.

The strip T comprising a portion of the treadle is shown in FIGURE 2 with the several layers broken away to permit illustration. The treadle T comprises a bottom or outer casing 14 which may be made of any appropriate wear-resistant material such as vinyl-coated nylon.

Substantial co-existance with this outer or bottom layer 14 is a lining 15 of vinyl. Superimposed on this lining 15 but not co-extensive therewith is a bottom layer 16 of sponge rubber. This layer 16 is narrower than the layers 14 and 15 for a purpose later to be described.

Extending over the inner or upper face of the foam rubber layer 16 is a contact in the form of a metallic foil such as aluminum and designated 17. A lead wire such as represented at 18 is connected at thec-ontact 17 as reppresented at 19. It is notable at this point that the contact 17 is somewhat narrower than the foam rubber layer 16.

Positioned over the contact 17 is an intermediate layer which has an extent comparable to that of the bottom layer 16 and is formed with a plurality of holes or openings 21. The size and spacing of these openings 21 is an important feature of the invention because it is the size and spacing of these openings which determine the sensitivity of the treadle.

Above the intermediate layer 20 there is a second contact 22 which also takes the form of aluminum foil. A lead wire 23 is connected to the contact 22 as indicated at 24. This contact 22 is carried on the inner or lower face of an upper layer 25 of foam rubber, Covering this upper layer 25, is a layer 26 of vinyl and this is in turn covered by an upper layer 27 of the wear-resisting casing which in this case is a vinyl-coated nylon.

It will be noted that there is a marginal edge of vinyl and the casing about the layers of foam rubber. The side edges are represented at 28 and the end edges at 29. It is evident that with the top and bottom layers of the foam rubber carrying the strips of aluminum foil and the intermediate layer 20 therebetween that the layer of vinyl and the casing may be positioned whereupon the assembly is introduced to a press which seals the marginal edges 28 and 29 by heat and pressure.

FIGURE 6 is representative of an electrical circuit in which the treadle T may be included. In this case the electrical circuit is used to sound an audible alarm when a predetermined pressure is applied to the treadle T. Thus, the lead wire 23 is shown as connected to a bell 30 3 with a control switch 31 included and the power source is represented at 32. It is evident with the switch'lal closed that when pressure is applied to the treadl-e T to cause the contacts 17 and 22 to come into engagement,

"the bel-l'30will'be energized.

FIGURE 4 is typical of an intermediate layer 2! that is used when a low degree of sensitivity is desired, that is when it is desired that the circuit-be closed only when a relatively great pressure is applied to the treadle. In FIGURE 4 the openings '21 are comparatively small and are widely spaced. FIGURE 5 is in contrast to FIGURE '4 because in this view the openings 21 are larger and more closely spaced. -'With such a layer 20 included, a smaller pressure energize the circuit because it will cause engagement of the contacts17 and 22.

FIGURE 3 illustrates how pressure applied to the treadle 'T :such as by persons stepping on the doormat 13 and will cause the contacts 17 and 22 to come into engage- .ment and close the circuit.

While arpreferred specific embodiment of the invention is hereinbefore set forth, it is to be clearly understood that the invention is not tobe limited to the exact construction, materials, and designs illustrated and described because various modifications of these details may be provided in putting the invention into practice within the purview oft-he appended'claim.

Whatis claimed is:

A self contained electric mat switch comprising, in combination, a bottom layer of foam rubber having an of foam rubber having spaced openings and interposed between said foil layers and in engagement'therewith, said foil layers being normally spaced apart by said intermediate layer but adapted to engage one another through certain of said openings when pressure is applied to said top foam rubber layer, an electric conductor connected to each of said foil layers and included in the circuitto be controlled by said mat switch, and a moisture proof casing about said foam rubber and foil layers.

References Cited by the Examiner UNITED STATES PATENTS 2,783,327 2/1957 Luckey ZOO-86 2,954,446 9/ 1960 Wikkerink ZOO-86 3,056,005 9/1962 Larson ZOO- 86 3,133,167 5/1964 Miller ZOO-86 X BERNARD A. GILHEANY, Primary Examiner.

ROBERT K. SCHAEFER, Examiner.

H. A. LEWITTER, Assistant Examiner. 

